For gluing magnets you will need magnets of size: 30 mm length, 10 mm width, 5 mm thickness - 78 pcs. Magnets need to be glued three in a row, recall that there are 26 magnetic poles.
It is recommended to use glue "super moment" liquid (not gel), two tubes are enough. As a dehydrator, you can use alcohol or another solvent and a napkin. You will also need: paper stationery tape, aluminum tape, two-component epoxy adhesive.
A little bit about glue compositions.
Some may say, and this is partly true, super glue, but on it magnets will simply tear off. Yes, it can tear, but for the first stage of sticking this is more than enough. Of course, subject to all the rules glued do not touch, do not move, do not worry until complete polymerization and setting the glue.
We draw your attention to the safety precautions when working with magnets, they are small and fragile, they can burst even with a sharp magnetization to metal. Moreover, at the time of destruction, these pieces can scatter in different directions with great force.
Before starting work, degrease the surface. and we begin to glue the magnets in a full circle, glue through the pole, first we glue completely one type of poles (north or south) on the circle, and then we place the second type of poles between them.
We initially apply 3 magnets that will form the pole in order to determine their symmetrical location in the future. Magnets are declared as 30 mm, but they can sometimes be 29.5 mm.
The gluing is done in a full circle, that is, the order of gluing is not in length, but in a circle. The first circle, then 2, then 3. To glue the magnets through the pole, first of all we glue the completely north or south poles on the circle, and then we place the south or north poles between them.
Using the gluing axis for the first magnet, we use our drawn line, that is, we put the magnet tightly on the line on one or the other side, not in the middle between the two lines, but on one of them.
On this project, we will try to apply a pole shift, so to speak, respectively, we glue the first magnet to one line, and the last to the other, and the second magnet will be located exactly in the middle. And such a bevel will be performed in a circle.
The gluing technique is as follows: put a magnet and neatly droplets into the gap between the magnet and the iron poured a thin strip of glue, the same thing is done on the other side. It is for this that you need liquid super glue, it flows perfectly there, although it may seem not so at first. Everything, leave it to dry, do not move, let it set.
This technique is more practical and you get less dirty than when you apply glue to a magnet and then try to glue it, move it, get your hands dirty and glue the metal around the magnet.
The next magnet should also be of the same pole, that is, when checking with the previous one, it should be attracted. In this case, we put it next to leaving a gap for the magnet with the other pole and move the lines on the same side as the previous magnet and gently add glue. Yes, and do not forget to degrease the surface anyway, because you touch both the rotor and the magnets with your hands, so if possible, do this more often.
No need to pour a lot of glue; you will see how the capillary forces of the glue begin to pull the glue under the magnet. Try not to pour onto the metal outside the magnet, this is necessary to leave not a dried glue, but a metal base for the adjacent magnet for gluing.
Be sure to check the polarity every time. Each one has different skills, so you can pre-take and paint the north and south poles with some non-erasable marker and then glue them, but be sure to pay attention, paint only the side that you will not stick to the metal, that is, so that the other side is clean .
For skeptics who can say that such a sticking is not suitable, the glue will not leak under the magnets, we will explain. You doubt correctly, do what you look at and with skepticism correctly.
Suppose a magnet is placed on the circumference of the rotor, even if it is a small magnet, it is flat and it touches the surface, we can say one point. And this spot of metal-to-metal contact is very small and we have gaps that in any case arise. It is in these cavities with such magnets that glue flows with the help of the capillary effect. Therefore, the glue fills the area well for sufficient gluing of the magnet to the metal.
The hypothetical north in the front row is pasted, you can proceed to gluing the south. Why glued through a magnet, explain. Now the magnet is between 2 poles of opposite polarity, and it can be beautifully neatly placed exactly in the middle and it will not stretch either left or right. Now, in this gap, we pour liquid superglue into the magnet’s corner in the same way. Pay attention, getting there with your nose, right in the corner, does not work. Therefore, we make droplets there and then inflate. Be careful, superglue is very toxic, so do not take a breath next to it.
Do not pour in the end yet, because the next magnet will fit tightly to it, it is necessary that it rests not on a sticker, but on pure metal.
Please note that in the gap between the magnets you need to drip glue, and not to fill it with superglue. The filling will be carried out in the second stage using epoxy resin.
After the first row is sealed, you need to let it dry for at least an hour, because the glue is still liquid there.
A rotor with one row of magnets can already be installed in the stator and twisted, so you can see its sticking.
After installing the rotor, a gap became noticeable, this happened due to the fact that the estimated height of the magnets was 5 mm, in fact it turned out 4.7 - 4.8 mm, as a result, a gap of 0.7 mm to the side was obtained.
Install the cover and check sticking on one row of magnets.
Preliminary sticking data with one row of magnets showed 0.44 Nm.
Glue the second row of magnets and check sticking.
After sticking test they saw 0.53 Nm.
The third row is sealed, let dry and again we carry out the sticking test.
Weighed the load and begin to move. We measure and see 85 mm.
We calculate by the formula:
(acceleration of gravity)
- weight in kg (in our case, a weight of 1 kg)
- shoulder length in meters
Find the moment to break:
With a straining moment of 0.83 Nm, the generator rotates silently. This is another feature of regular Bavaria, the generator is silent.
The all-metal rotor that is used here seems to be the more correct solution. Since it is not all-metal, but machined with a squirrel cage, it violates absolutely any calculations of Bavaria and the fight against sticking. Such conclusions can be obtained based on the experience of previous designs, which were built according to the same scheme, but with a machined rotor. Therefore, all further designs will be assembled only on an all-metal rotor for gluing magnets according to the Bavarian scheme.
The next part will examine how magnets need to be filled with epoxy. It seems nothing complicated, but again, there are nuances.